#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <errno.h>
#include <sys/wait.h>
#define PPPD_PATH "/usr/sbin/pppd"




int main(int argc, char **argv)
{
    char *server = NULL;
    char *mode;
    int srv;


    int port, conn_s;
    struct sockaddr_in serv_addr, client_addr;
    int cliaddr;



    int readpipe[2], writepipe[2];

    unsigned char buf[1024];

    int ret=0;

    if (argc == 1)
    {
        printf("no arguments!\n");
        return 0;
    }
    mode = argv[1];

    if (strcmp(mode, "server")==0)
    {
        srv = 1;
    }
    else if (strcmp(mode, "client") == 0)
    {
        srv = 0;
    }
    else
    {
        printf("wrong argument!\n");
        return 0;
    }

    pipe(readpipe);
    pipe(writepipe);



    port=socket(AF_INET, SOCK_STREAM, 0);


    if (srv == 0)
    {
        int portn;
        port=socket(AF_INET, SOCK_STREAM, 0);
        sscanf(argv[3], "%i", &portn);


            serv_addr.sin_family = AF_INET;
            serv_addr.sin_addr.s_addr = inet_addr(argv[2]);
        serv_addr.sin_port = htons(portn);

            ret = connect(port, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
            if (ret < 0)
            {
                    printf("server not found\n");
                    return (0);
            }
        conn_s = port;
    }
    else
    {
        int portn;
        sscanf(argv[2], "%i", &portn);
        serv_addr.sin_family = AF_INET;
            serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
            serv_addr.sin_port = htons(portn);

            bind(port, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
            listen(port, 1024);
        conn_s = accept(port, NULL, NULL);
                printf("Accepted!\n");
    }
    ret = fork();
    if (ret < 0)
    {
        printf("fork failed!\n");
        return 0;
    }
    else if (ret == 0)
    {

        ret = fork();
        if (ret == 0)
        {
            printf("PPP\n");
            dup2(readpipe[0], 0);
            dup2(writepipe[1], 1);

            close(readpipe[0]);
            close(readpipe[1]);
            close(writepipe[0]);
            close(writepipe[1]);

            if (srv == 0)
            {
                execl(PPPD_PATH, "nodetach", "notty", "noauth", NULL);
            }
            else
            {
                execl(PPPD_PATH, "nodetach", "notty", "noauth", "persist", "passive", NULL);
            }
        }
        else
        {
            int code;
            close(readpipe[0]);
            close(readpipe[1]);
            close(writepipe[0]);
            close(writepipe[1]);

            wait(&code);
            printf("PARENT: Код возврата PPPD:%d\n", WEXITSTATUS(code));

        }
    }
    else
    {
        printf("PPP id = %i\n", ret);
        unsigned code = 0;
        while (1)
        {
            int cnt;
            cnt = read(writepipe[0], buf, 1024);
            if (cnt > 0)
            {
                send(conn_s, buf, cnt, MSG_DONTWAIT);
                printf("send %i\n", cnt);
            }

            cnt = recv(conn_s, buf, 1024, 0);
            if (cnt > 0)
            {
                printf("Receive %i\n", cnt);
                write(readpipe[1], buf, cnt);
            }
        }


    }
    return 0;
}